Conventionally, a vehicle is equipped with vehicle-installed electric equipment such as a windshield wiper unit, a power window unit, and a power slide door unit. The vehicle-installed electric equipment is provided with an electric motor as a motive power source and is configured such that the motive power of the electric motor actuates actuation members such as a wiper arm, door glass, door, etc. A speed-reduction mechanism (motive-power transmission mechanism) is provided on a route for transmitting the motive power of the electric motor. The speed-reduction mechanism is accommodated in a hollow housing for the purpose of, for example, preventing foreign substances from entering between elements forming the speed-reduction mechanism. A yoke accommodating the electric motor is installed to the exterior of the housing, and the output shaft of the electric motor is inserted into the housing.
Japanese Patent Application Laid-Open Publication No. 2008-236995 discloses an example of an electric motor apparatus having such an arrangement. The motor apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 2008-236995 is used for a wiper motor. The wiper motor includes a motor subassembly (electric motor) forming the motor apparatus and a speed-reduction portion assembly. The motor subassembly includes a yoke having a bottomed shape, an armature accommodated in the yoke, an armature shaft which rotates together with the armature, a commutator provided on the armature shaft, and a brush holder unit which supplies power to the armature via the commutator. A first flange portion is formed on the yoke so as to extend from the opening end to the outer circumference side. The brush holder unit includes a brush holder, a pair of brushes, and internal wirings as main components.
The brush holder forming the brush holder unit includes a cylindrical holder main body portion and a second flange portion extending outward in the radial direction from the holder main body portion. In addition, the brush holder includes a flat plate portion extending from the second flange portion in the widthwise direction and a connector box (connector unit) formed on the distal end side of the flat plate portion. The respective portions of the brush holder are integrally formed by injection molding using a resin material. Furthermore, an external connector is detachably connected to the connector box to electrically connect the internal wirings to an external power source, operation switches, and the like.
On the other hand, the speed-reduction portion assembly includes a gear housing (housing). The third flange portion is integrally formed on the gear housing so as to extend from an end portion on the yoke side to the outer circumference side. The third flange portion abuts on an end face of the first flange portion, with the second flange portion being sandwiched between them, and is fastened/fixed to the first flange portion with a plurality of screws. This makes the direction along the axis of the armature coincide with the assembling direction of the brush holder unit with respect to the yoke and the assembling direction of the speed-reduction portion assembly with respect to the brush holder unit.
The speed-reduction portion assembly is placed in the gear housing. The gear housing has an opening portion on the bottom surface side. A cover member closes the opening portion. The speed-reduction portion assembly includes a worm as the first gear and a worm wheel as the second gear which form a speed-reduction mechanism (motive-power transmission mechanism). The worm is coaxially disposed with the armature shaft and is coupled to the armature shaft through a coupling so as to transmit torque to it while a motor assembly is being coupled to the speed-reduction portion assembly.
On the other hand, the rear wiper motor (electric motor apparatus) disclosed in Japanese Patent Application Laid-Open Publication No. 2008-199695 is installed to each back door of a vehicle through a metal bracket. This rear wiper motor is formed by an armature which rotates by energization, a flat cylindrical yoke accommodating the armature, and a gear case coupled to the yoke and having a wiper shaft which has a thread portion formed on the distal end of a pivot shaft which rotates through a speed-reduction mechanism, with the wiper shaft extending outward. A plurality of fastening portions are formed around the gear case in the shape of thick flanges. While the bracket is covering the opening of the gear case, the plurality of fastening portions are fastened/fixed to the bracket with screws. Japanese Patent Application Laid-Open Publication No. 2008-199695 has no description about how components such as a connector forming part of a circuit which supplies power to the rear wiper motor are provided in the gear case.